This project is directed toward an experimental investigation of behavioral and pharmacological factors which control self-administration of various drugs of abuse. The specific focus is upon evaluation of and manipulation of subject preference for different concurrently available compounds or different dosages of the same compound. Laboratory primates, equipped with indwelling venous catheters which permit self-infusion of various drug compounds, serve as subjects. The subjects, under conditions of a continuously monitored and controlled behavioral environment, will be studied with respect to their self-selection and infusion of various concurrently available pharmacological compounds. This permits experimental evaluation of those factors which influence self-selection of one drug over another, and evaluation of behavioral procedures for transferring behavioral dependence from one drug compound to another. The ultimate goal is to develop and demonstrate an experimental model for attenuating behavioral dependence upon high addiction liability compounds by means of gradually shifting the animals' behavior toward other less addictive or neutral compounds.